Green Economy in a Blue World-Full Report

Threats: • Piling noise/construction activities; • Habitat loss for sea ducks and divers; • Migration barriers for birds, sea turtles and whales; • Bird collisions; • Seabed changes; • Navigational hazards/oil spills. Opportunities: • Exclusion of other activities, such as trawling; • Habitat structuring. Tidal energy The impacts of tidal energy infrastructure vary significantlydependingon thedesignemployed. Tidal barrage systems that extract energy from ranges in tides have similar environmental impacts as traditional dams (Wilhelmsson, et al., 2010): Other devices such as tidal fences or individual turbines may cause fewer negative impacts on the marine environment, compared to barrages, as their impact is spread out over a larger area. Remaining impacts are linked primarily to the effect of moving parts on marine mammals (IPCC, 2011). Wave energy Similar to tidal energy, the impacts of wave- energy technologies are specific to the site and type of device. For wave projects, similar concerns exist with regard to interference with fish or marine mammal migration (because wave systems are closed, entrainment is not an issue), reduction of wave height and release of lubricants used within wave systems. Apart from offshore wind, there are few full-scale marine-basedrenewableenergyprojectsdeployed at full scale and as such, relatively little is known about the real impacts of newer technologies. Therefore, it is important that new developments are accompanied by appropriate monitoring and evaluation as part of environmental impact assessment procedures. Admittedly, this comes at a cost. The Ocean Renewable Energy Coalition (2011) estimates the environmental costs associated with the permitting of small marine renewable projects (under 1 MW) can make up as much as 40 per cent of the overall project cost. However, this investment is still recommended to Threats: • Habitat changes; • Sedimentation (requiring dredging); • Marine migration barriers; • Change in estuarine water flow.

While the environmental risks and opportunities of different technologies are specific to the source and design as well as the specific site, some general assumptions can be drawn. The greatest negative impacts are most likely during piling, construction and decommissioning due to noise and habitat loss. During operation, moving parts can affect birds, fish and sea mammals. But many of the potential negative impacts can be avoided if ecologically-sensitive sites are not developed, and best practice is employed for design. Furthermore, it is possible that the marine environment can benefit from the presence of the energy infrastructure through the creation of artificial habitat and the reduction of other adverse activities, like no fishing in the area (Wilhelmsson, et al., 2010). Marine energy does not directly emit CO 2 during operation; however, GHG emissions may arise from different aspects of the lifecycle of ocean energy systems, including raw material extraction, component manufacturing, construction, maintenance and decommissioning. A comprehensive review of lifecycle assessment (LCA) suggests that lifecycle GHG emissions from wave and tidal energy systems are less than 23 grams CO 2 eq per kWh (IPCC). It is difficult to assess the environmental impacts of wave-energy technologies, due to the limited experience of deployment. The potential effects will vary by technology and location, but may include competition for space, noise and vibration, electromagnetic fields, disruption to biota and habitats, water quality changes and possible pollution. For instance, noise and vibration are likely to be most disruptive during construction and decommissioning, while electromagnetic fields around devices and electrical connection/export cables that connect arrays to the shore may be problematic to sharks, skates and rays that use electromagnetic fields to navigate and locate prey. Chemical leakage due to abrasion (of paints and anti- fouling chemicals) and leaks, for example, oil leaks from hydraulic power take-off systems are also potential negative environmental impacts of wave energy (IPCC). Proper planning and management of offshore wind farms can help to ensure that population sizeandstructureofmarine life isnot significantly disturbed and can potentially enhance levels of marine species (Wilhelmsson, et al., 2010). However, if not well-managed, significant risks for the marine environment include: 2.3.5 Potential risks and opportunities Offshore-wind energy

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